C++

[wjmcumt]

各位帮忙看一下这个程序（不知错在哪儿）：
#include<iostream>
using namespace std;
template<class ElemType>
class StackSq
{
ElemType *Stack;//存栈元素
int top;//存栈顶元素位置
int MaxSize;//
public:
StackSq(int ms);//
void Push(ElemType item);//
ElemType Pop();//
ElemType Peek();//
bool EmptyStack();//
~StackSq();//
void AllotStack();//
};
template<class ElemType>
StackSq<ElemType>::StackSq(int ms)//
{
if(ms<=0){cout<<"ms值非法！"<<endl;exit(1);}//
MaxSize=ms;//
Stack=new ElemType[ms];//
if(!Stack)
{
cerr<<"Memory allocation failure!"<<endl;
exit(1);
}
top=-1;//
}
template<class ElemType>
void StackSq<ElemType>::Push(ElemType item)//
{
if(top==MaxSize-1) AllotStack();//
top++;//
stack[top]=item;//
}
template<class ElemType>
ElemType StackSq<ElemType>::Pop()//
{
if(top==-1)
{cerr<<"Stack is empty!"<<endl;
exit(1);
}//
top--;//
return satck[top+1];//
}
template<class ElemType>
ElemType StackSq<ElemType>::Peek()//
{
if(top==-1)
{cerr<<"Stack is empty!"<<endl;
exit(1);
}//
return stack[top];//
}
template<class ElemType>
bool StackSq<ElemType>::EmptyStack()//
{return top==-1;}
template<class ElemType>
StackSq<ElemType>::~StackSq()//
{
delete []stack;
stack=0;
top=-1;
MaxSize=0;
}
template<class ElemType>
void StackSq<ElemType>::AllotStack()//
{
ElemType *p=new ElemType[2*MaxSize];
MaxSize*=2;//
for(int i=0;i<=top;i++)
p[i]=stack[i];//
delete []stack;//
stack=p;
}
double Compute(char *str)//
{
StackSq<double>S(5);//
double x,y;
int i=0;//
while(str[i])//
{
if(str[i]==' '){i++;continue;}//
switch(str[i])
{
case '+'://
x=S.Pop()+S.Pop();
i++;break;
case '-'://
x=S.Pop();//
x=S.Pop()-x;//
i++;break;
case '*'://
x=S.Pop()*S.Pop();
i++;break;
case '/'://
x=S.Pop();//
if(x!=0.0)
x=S.Pop()/x;//
else
{cerr<<"Divide by 0!"<<endl;
exit(1);
}
i++;break;
default://
x=0;
while(str[i]>=48&&str[i]<=57)
{x=x*10+str[i]-48;i++;}//
if(str[i]=='.')//
{
i++;
y=0;
double j=10.0;//
while(str[i]>=48&&str[i]<=57)
{
y=y+(str[i]-48)/j;
i++;j*=10;
}
x+=y;//
}
}
S.Push(x);//
}
if(S.EmptyStack())
{cerr<<"Stack is empty!"<<endl;
exit(1);
}//
x=S.Pop();//
if(S.EmptyStack()) return x;
else
{cerr<<"expression error!"<<endl;
exit(1);
}
}
int Precedence(char op);//
void Change(char *s1,char *s2)//
{
StackSq<char>R(5);//
R.Push('@');//
int i=0,j=0;//
char ch=s1[i];//
while(ch!='\0')
{
if(ch==' ') ch=s1[++i];//
else if(ch=='(')
{R.Push(ch);ch=s1[++i];}//
else if(ch==')')//
{
while(R.Peek()!='(') s2[j++]=R.Pop();
R.Pop();//
ch=s1[++i];
}
else if(ch=='+'||ch=='-'||ch=='*'||ch=='/')//
char w=R.Peek();
while(Precedence(w)>=Precedence(ch))
{//
s2[j++]=w;R.Pop();
w=R.Peek();
}
R.Push(ch);//
ch=s1[++i];
}
else
{//
if((ch<'0'||ch>'9')&&ch!='.')
{cout<<"中缀表达式错误！"<<endl;
exit(1);//
}
while((ch>='0'&&ch<='9')||ch=='.')//
{
s2[j++]=ch;
ch=s1[++i];
}
s2[j++]=' ';//
}
}
ch=R.Pop();//
while(ch!='@')
{if(ch=='(')
{ cerr<<"expression error!"<<endl;
exit(1);
}
else {
s2[j++]=ch;
ch=R.Pop();
}
}
s2[j++]='\0';//
}
int Precedence(char op)//
{
switch(op)
{
case '+':
case '-':
return 1;//
case '*':
case '/':
return 2;//
case '(':
case '@':
default:
return 0;//
}
}
double Compute(char *str);
void Change(char *s1,char *s2);
void main()
{
char a[50],b[50];
cout<<"请输入一个中缀算术表达式："<<endl;
cin.getline(a,50);
Change(a,b);
cout<<"中缀："<<a<<endl;
cout<<"后缀："<<b<<endl;
cout<<"求值："<<Compute(b)<<endl;
}

[gykgod]

垃圾玩意